Question

Lyme disease is an infection caused by bacteria. A test for Lyme disease may be affected by other medications and medical conditions. The testing results are summarized in the table.

Tested positive Tested negative Row Totals
Has Lyme disease 53% 17% 70%
Does not have Lyme disease 12% 18% 30%
Column Totals 65% 35% 100%


What percentage of all patients who took the test had a true negative result?
35%
30%
18%
12%

Answer 1

18% of all patients who took the test had a true negative result

Explanation:

We have the table,

Tested positive Tested negative Row Totals

Has Lyme disease 53% 17% 70%

Does not have Lyme disease 12% 18% 30%

Column Totals 65% 35% 100%

True negative means that they had did not have Lyme disease and they tested negative as well.

So, this corresponds to the 2nd row and the 2nd column, which has 18%